Transition to turbulence in pipe flow

We review the results of recent experimental investigations into transition to turbulence in fluid flow through a circular straight pipe, at room temperature. The stability of Hagen - Poiseuille flow was investigated using impulsive perturbations by either injecting or sucking small amounts of fluid through holes in the wall of the pipe. The evolution of the induced patches of disturbed flow were observed using flow visualization and laser Doppler velocimetry. The principle result obtained was a finite amplitude stability curve where the critical amplitude of the disturbance required to cause transition is found to be inversely proportional to the Reynolds number. Estimates for the lower threshold value of Reynolds number which is required to sustain turbulence were also measured. © 2006 Springer Science+Business Media, LLC.